PCB needs to go through numerous known processes to obtain the final product. However, PCB manufacturing may encounter errors or defects at certain times, in which case the PCB needs to go through a rework process to ensure the overall performance of the finished PCB. Here, we will explore the PCB rework process.
What is PCB Rework?
Any process of revising, correcting or improving in PCB manufacturing is referred to as PCB rework. Product manufacturing and assembly are critical processes with the possibility of numerous errors and faults. Organisations take many proactive measures to reduce errors in products. Still, some errors remain in the produced units. These errors affect the overall performance and quality of the product, sometimes leading to the product failure stage.
Similarly, PCB is also a manufactured and assembled product. Many defects are left during the manufacturing and assembly process. Removing these errors and faults is known as PCB rework. Circuit board rework is done to make PCB error-free. Rework saves a PCB from scrap. If there is no rework, then there will be extra manufacturing required to compensate for the defective quantity. This will lead to monetary and time loss for PCB manufacturers. To maintain efficiency in production and cost control, PCB rework is also done along with quality measures.
The PCB rework is also done in some special cases of design change or modification in the circuit. PCBs are the physical transformation of the electrical and electronic circuits. If any minor design change occurs after product launch or validation, it may require us to make small changes in the PCB assembly. Replacing or removing any components, shorting or disconnecting tracks, and making additional holes or vias are done in these types of scenarios.
Importance of PCB Rework
PCB rework activities are done to remove defects in existing products. This saves additional manufacturing time and costs for the new products. Circuit board rework is done by PCB manufacturers along with the assembly process and repair after the sale of the product. During product inspection, if any minor or repairable defect is found, it is removed by repairing techniques. Rework on PCB makes it perfect for further use. If the PCB manufacturers scrap all the defective PCBs, then it will lead to material loss, time loss and money loss. The rejected PCBs will not be further useful and will increase in garbage. Thus, rework on PCB sometimes becomes useful for PCB manufacturers.
PCB rework in the design change case saves additional manufacturing time and resources for the newer version of the PCB. This also improves circuit configuration for users. The older version of PCB can be modified and used as the latest version.
PCB Rework Process
Rework and repairing any PCB are itself a critical task for PCB manufacturers. Though many manufacturers offer different PCB rework services, it requires proper setup with standard procedures to follow.
- Defect Identification – Any PCB which is separated as defective during assembly or application, is analysed for potential defects. Defects can be of major or minor type, depending upon the severity. Analysing the type of defect describes the nature of the defect, time required, resources required and a lot of other relevant information. Additionally, the cause of the defect is also sometimes identified for future modifications and upgrades.
- PCB Rework and Repair Process – The circuit board rework and repair process can be a component replacement, shorting or breaking tracks, pad repair, via repair, soldering or desoldering. The rework is done without affecting the original functionality of the PCB.
- Validating the Rework – The repaired or reworked PCB is tested and validated properly via visual checks, electrical tests and functional tests. All the checks and tests are mandatory for product quality and reliability. If any other defect is found during these processes, the rework is done again by following all the steps.
- Documentation Process – All the processes and tasks are properly documented and recorded by PCB manufacturers for future reference. The rework data is further used to improve the assembly and manufacturing process. Based on the component failure rate, component suppliers and manufacturers are also updated accordingly.
Challenges in PCB Rework
PCB rework and repairing tasks are always challenging for the PCB manufacturers on many factors.
- Requires Skilled and Experienced Manpower – Circuit board rework and repair work on PCB to be done by skilled and experienced manpower only. Understanding the circuit design effectively, adequate knowledge of PCB manufacturing and assembly process and good knowledge of electronics concepts are required in the manpower for rework. Lack of knowledge and skill may result in other failures and defects..
- Additional Resources Required – Manufacturing and assembly of the PCB requires complete setup. Rework is an additional activity apart from the manufacturing process. For this, additional setup and process are required, as rework and repair cannot be done along with the continuous line production. Setting up the process for rework costs additional for PCB manufacturers. Similar equipment, testing setup and machines are also required in the rework process. Thus, the rework cost should be under the PCB manufacturer’s control. Higher costs for PCB rework are not recommended.
- Integrity of the Rework – The rework should be done smoothly on the PCB without affecting its core functionality and other components’ working. If the complexity of the circuit is high and the size of the PCB is compact, the PCB rework becomes difficult.
- The Configuration of the Component – PCB rework depends upon the manufacturing and assembly methods of the components. Any PCB part or component, which is complex to replace or repair, can be a blockage in circuit board rework.
- Time Factor – For any user and application, time will always be a key factor. If any PCB takes too much time for rework, the availability of the required components and resources are time-dependent, and transportation time to repair location is high, then it becomes critical for PCB manufacturers for rework. Maintaining the time limit for the PCB rework is always a high priority.
- Remaining Operating Time – Each product and component has its own life cycle and operating range. PCB rework can remove the defect at the time, but cannot increase the overall lifetime of the PCB. Other parts of the PCB, which are not defective, have operated for a time. Thus, the reworked PCB may no longer be in use as required.
Summary
It can be seen that PCB rework is an additional activity for PCB manufacturers, resulting in additional budget and resources. In future, advanced rework methods can be seen in PCB like automation and artificial intelligence. With a proper design plan and manufacturing processes, the scope of rework can be limited for the products. In addition, reliable PCB rework services are a must-be to get a perfect PCB.
